A highly sensitive fiber-tip temperature sensor based on enhanced Fresnel reflection induced by modified materials

A material-modified Fresnel reflection enhancing high-sensitive fiber-tip temperature sensing method is theoretically proposed and experimentally demonstrated. High refractive index semiconductive nano-ZnO and nano-TiO2 as doping materials enhance the Fresnel reflection in fiber tip probes, and the interference spectrum of these reflected light shows better sensing performance than when undoped. On this basis, the sensitivity is further improved by utilizing ultraviolet (UV) irradiation due to the UV sensibility of the modified materials. By comparing the sensing performance of different material-doping sensing probes, the ZnO-doped fiber tip sensor witnesses the highest temperature sensitivity, which is 94.1 pm/°C. Thanks to the positive role of UV irradiation, this number increases to 141 pm/°C. The proposed fiber tip sensor has a sturdy structure, simple and economical preparative process, competitive sensitivity, high linearity, satisfactory repeatability, and stability. The micron-scale reflective probe enables better detection of extreme environments and can be expected to conduct high-sensitivity temperature sensing in industrial, biomedical, chemical, environmental, and military regions.